Antenna structure and wearable device

Abstract

The present disclosure relates to the technical field of electronic equipment, and specifically provides an antenna structure and a wearable device. The wearable device includes a metal shell, the shell includes a bottom shell and a frame that surrounds the edge of the bottom shell and is integrally connected to the bottom shell, and the antenna structure includes: a slit opened on the frame, the slit has a first end and a second end located on opposite sides in a first direction, and the first direction is a direction surrounding the edge of the bottom shell; the slit is provided with an opening at the first end, and the opening faces the side away from the bottom shell; in the first direction, the length from the first end of the slit to the ground end is 1 / 4 of the working wavelength; the feeding terminal is provided between the first end of the slit and the ground end, and is located close to the ground end. The antenna structure disclosed in the present invention has a smaller slit length, and the structural strength and appearance integrity of the shell are better.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electronic equipment, and in particular to an antenna structure and a wearable device. Background Art

[0002] With the development of electronic devices, smart wearable devices are becoming more and more popular among users due to their diverse functions. Take smart watches as an example. In addition to the basic timing function, general smart watches also integrate many functions such as sports assistance, track positioning, and connection with smart terminals. In order to achieve these functions, smart watches need built-in antennas to receive and radiate signals. For example, in order to receive GPS signals, the watch needs a GPS positioning antenna; for another example, in order to interact and connect with mobile phones, the watch also needs a Bluetooth antenna, etc.

[0003] With the development of wearable devices, more and more smart watches use all-metal shells. An all-metal shell means that the bottom shell and the middle frame of the watch are both made of metal materials. In particular, the all-metal shell can be made by integrally forming the bottom shell and the metal middle frame, or it can be electrically connected together by connection methods such as screws. The metal shell has better protection capabilities and also greatly improves the appearance quality and grade of the watch. However, the all-metal shell also shields the built-in antenna of the watch, which brings difficulties to the design of the antenna. Therefore, how to achieve the antenna design of the all-metal shell has become an important research direction. Summary of the invention

[0004] In order to realize the antenna design of a full metal shell in a wearable device, an embodiment of the present disclosure provides an antenna structure and a wearable device.

[0005] In a first aspect, an embodiment of the present disclosure provides an antenna structure applied to a wearable device, wherein the wearable device includes a metal shell, wherein the shell includes a bottom shell and a frame surrounding an edge of the bottom shell and integrally connected to the bottom shell, wherein the antenna structure includes:

[0006] A slit is provided on the frame, wherein the slit has a first end and a second end located on opposite sides in a first direction, wherein the first direction is a direction surrounding the edge of the bottom shell; the slit is provided with an opening at the first end, wherein the opening faces a side away from the bottom shell; and in the first direction, a length from the first end of the slit to a ground end is 1 / 4 of an operating wavelength;

[0007] The feeding terminal is arranged between the first end of the slot and the ground end, and is located close to the ground end.

[0008] In some embodiments, the second end of the slot forms the ground end.

[0009] In some embodiments, the antenna structure further includes:

[0010] A grounding terminal is provided in the slot and located between the first end and the second end. The grounding terminal divides the slot into an independent first sub-slot and a second sub-slot in the first direction. The grounding terminal forms the grounding end.

[0011] In some embodiments, a groove is formed on the outer side wall of the second end of the slit, and the groove is symmetrical with the opening in a first direction.

[0012] In some embodiments, the gap is filled with an injection-molded structure that matches the shape, and the injection-molded structure is a non-metallic material.

[0013] In some embodiments, the antenna structure further comprises:

[0014] The first capacitor is arranged in the gap, and the two electrodes of the first capacitor are respectively connected to the two sides of the gap width direction; in the first direction, the first capacitor is located at one end close to the opening.

[0015] In some embodiments, in the first direction, the distance between the feeding terminal and the ground end is a first length, the distance between the first end and the ground end is a second length, and the ratio of the first length to the second length is 0.1 to 0.2.

[0016] In a second aspect, an embodiment of the present disclosure provides a wearable device, comprising the antenna structure according to any embodiment of the first aspect.

[0017] In some embodiments, a Bluetooth antenna and a satellite positioning antenna are included, and the Bluetooth antenna and the satellite positioning antenna are the antenna structure and are respectively arranged on opposite sides of the frame;

[0018] The first slot of the Bluetooth antenna and the second slot of the satellite positioning antenna are symmetrical in shape, and the length from the first end of the first slot to the ground end is 1 / 4 of the working wavelength of the Bluetooth antenna, and the length from the first end of the second slot to the ground end is 1 / 4 of the working wavelength of the satellite positioning antenna.

[0019] In some embodiments, the wearable device is a smart watch or a smart bracelet.

[0020] The antenna structure provided in the embodiment of the present disclosure is applied to a wearable device, the wearable device includes an integrally connected all-metal shell, the antenna structure includes a slit opened on the frame, the slit has a first end and a second end opposite to each other in the first direction, the first direction is the circumferential direction of the frame, the slit is provided with an opening at the first end, and the opening faces the side away from the bottom shell, and the feed terminal is provided between the first end of the slit and the ground end, and is located near the ground end. By providing a slit on the frame, a slit antenna is formed, which is suitable for an all-metal shell. And an opening is provided at one end of the slit, so that the feed and the slit form a 1 / 4 wavelength slit antenna, that is, the length of the slit in the first direction is 1 / 4 of the working wavelength, which greatly shortens the length of the slit opening. On the one hand, the metal appearance is retained to the greatest extent, and on the other hand, because the slit is smaller, the shell has better integrity, which is convenient for improving the dust and water resistance level of the device, while meeting the use of miniaturized wearable devices.

[0021] The antenna structure provided in the embodiment of the present disclosure can form a ground terminal by the second end of the slot, or by setting a ground terminal in the slot. Thus, antenna switching of different wavelengths can be achieved by adjusting the position of the ground terminal, such as switching between a Bluetooth antenna and a satellite positioning antenna. And when the housing includes multiple antenna slots, the connection terminal is used to realize the construction of antenna structures of different wavelengths under the same slot shape, so that the appearance of the device is more integrated.

[0022] In the antenna structure provided in the embodiment of the present disclosure, a groove is provided on the outer side wall of the second end of the slot, and the groove is symmetrical with the opening shape in the first direction. The slot structure is made more symmetrical in appearance while ensuring the antenna performance remains unchanged, thereby improving the user experience. In addition, an injection molding structure of non-metallic material is filled in the slot to seal the slot, thereby achieving dust and water resistance of the device, and maintaining a consistent appearance of the shell, thereby improving the user experience.

[0023] The antenna structure provided in the embodiment of the present disclosure also includes a first capacitor, the two poles of the first capacitor are respectively connected to the two sides of the slot width direction, and in the first direction, the first capacitor is located at one end close to the opening. By setting the capacitor in the slot, the effective electrical length of the slot is increased, that is, at the same operating frequency, the slot length required by the antenna is shorter, further reducing the space occupied by the antenna structure.

[0024] In the antenna structure provided by the embodiment of the present disclosure, in the first direction, the ratio of the distance between the feed terminal and the ground terminal to the distance between the first end and the ground terminal is 0.1 to 0.2, so that the feed terminal is closer to the ground terminal, thereby making the most effective use of the slot length. In addition, the return loss (or matching degree) of the antenna can be optimized by adjusting the distance between the feed point and the ground terminal. When the feed terminal is located close to the ground terminal, the matching of the antenna is most easily adjusted to the best, thereby improving the antenna performance.

[0025] The wearable device provided by the embodiment of the present disclosure includes the antenna structure of any of the above embodiments, and thus has all the above beneficial effects. The device includes a Bluetooth and a satellite positioning antenna, and preferably the two antennas can be symmetrically arranged on opposite sides of the frame, so as to maintain the symmetry of the device structure in appearance, have a good look and feel, and improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1a It is a schematic diagram of the structure of a wearable device according to some embodiments of the present disclosure.

[0028] Figure 1b is a schematic diagram of the structure of a shell of a wearable device according to some embodiments of the present disclosure.

[0029] Figure 2 is a schematic diagram of an antenna structure according to some embodiments of the present disclosure.

[0030] Figure 3 It is a schematic diagram of the antenna structure in some other embodiments of the present disclosure.

[0031] Figure 4 is a schematic diagram of antenna structures in some other embodiments of the present disclosure.

[0032] Figure 5 is a schematic diagram of a filling structure in some other embodiments of the present disclosure.

[0033] Figure 6 is a graph of the return loss of the antenna structure according to some embodiments of the present disclosure.

[0034] Figure 7 is a graph showing the antenna efficiency of the antenna structure according to some embodiments of the present disclosure.

[0035] Figure 8 It is a schematic diagram of the antenna structure in some other embodiments of the present disclosure. DETAILED DESCRIPTION

[0036] The technical solution of the present disclosure will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described implementation is a part of the implementation of the present disclosure, rather than all the implementations. Based on the implementation in the present disclosure, all other implementations obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure. In addition, the technical features involved in the different implementations of the present disclosure described below can be combined with each other as long as they do not conflict with each other.

[0037] The antenna structure provided in the embodiments of the present disclosure is suitable for wearable devices with full metal shells. In smart wearable devices, multiple antennas are often included, such as Bluetooth antennas used to establish connections with smartphones; GPS antennas used for positioning; LTE antennas used to achieve base station communication, etc. The device radiates or receives signals through antennas.

[0038] Take smart watches as an example. Smart watches can generally realize functions such as sports assistance and track positioning, so they generally include at least a Bluetooth antenna and a satellite positioning antenna. In ordinary plastic shell watches, the built-in antenna can directly radiate and receive signals outward, and the antenna structure is easy to design. However, as the metal in the shell increases, it will shield the electromagnetic signal, and the design requirements of the antenna structure are getting higher and higher.

[0039] For example, the middle frame of some watches is made of metal, and the bottom shell is made of non-metallic materials such as plastic. In this case, the antenna can be realized through the gap between the metal middle frame and the motherboard, thereby radiating signals outward through the upper and lower sides of the middle frame. When the watch uses a full metal shell, for example, the bottom shell and the middle frame of the watch shell are integrally formed of metal materials, since the bottom shell is also made of metal, the antenna can no longer radiate through the gap between the motherboard and the middle frame, making the design of the built-in antenna much more difficult.

[0040] In the related art, in order to realize the antenna structure of the full metal shell, in some watches, a circular gap is opened in the middle of the middle frame, and the middle frame is divided into two independent parts, and the circular gap on the middle frame is used to form a slot antenna, and the slot antenna is used to radiate signals outward. This structure requires the metal middle frame to be completely divided, and non-metallic materials are injected into the circular gap to form an integrated appearance and seal, which greatly reduces the structural strength and dustproof and waterproof performance. In addition, the length of the gap surrounds the watch. After filling and injection molding, the appearance of the gap is abrupt, and the integrity is poor, which reduces the appearance and grade of the watch.

[0041] In order to solve the defects existing in the above-mentioned related technologies, in a first aspect, an embodiment of the present disclosure provides an antenna structure.

[0042] If the device volume allows, the antenna structure of the present disclosure can be used as various types of antennas in the device, such as Bluetooth antennas, GPS antennas, LTE antennas, etc. The wearable devices involved in the present disclosure can also be any type of device suitable for implementation, such as wrist-worn devices such as smart watches and smart bracelets; head-worn devices such as smart headphones and smart glasses; wearable devices such as smart clothing; etc., and the present disclosure does not limit this.

[0043] For ease of explanation, in the following embodiments of the present disclosure, a smart watch is used as an example of a wearable device. Figure 1a As shown, the smart watch includes a housing 100 and a screen 600 disposed at the front open end of the housing 100. Figure 1b As shown, the housing 100 includes a bottom shell 110 and a frame 120. The frame 120 surrounds the edge of the bottom shell to form a side middle frame. The bottom shell 100 and the frame 120 are both made of metal and are integrally formed. Figure 1b The middle shell structure is only used as an example. In other embodiments, there may be metal shells of any other shapes and structures. For example, the bottom shell 110 and the frame 120 may also be fixedly connected by screws or the like to form an integrated structure. Those skilled in the art should understand this, and the disclosure will not enumerate it.

[0044] In some embodiments, the antenna structure of the present disclosure includes a slot opened on the frame 120, and the slot has a first end and a second end opposite to each other in a first direction, and the first direction is the direction in which the frame 120 surrounds the bottom shell 110. The slot is provided with an opening at the first end, and the opening faces the side away from the bottom shell, and in the first direction, the length from the first end to the antenna ground terminal is 1 / 4 of the working wavelength. The antenna structure also includes a feed terminal, one end of which is connected to the feed module on the device motherboard, and the other end spans the slot and is located between the first end and the ground terminal and close to the ground terminal, so as to radiate electromagnetic wave signals outward through the slot.

[0045] From the above, it can be seen that the antenna structure of the embodiment of the present disclosure utilizes a slot antenna to realize an antenna structure of a full metal shell, which is suitable for wearable devices with metal shells, and improves the strength of the device and the integrity of the appearance. The slot antenna is arranged on the side frame 120 to prevent the antenna signal from being blocked when the device is worn, thereby improving the signal strength. By setting an opening at the first end, in the antenna structure, the feed and the slot form a 1 / 4 wavelength slot antenna, that is, the length of the slot in the first direction is shortened to 1 / 4 of the working wavelength. Compared with the related technology, the slot length can be halved, the length of the opening is reduced, and the metal appearance is retained to the greatest extent. The smaller slot also facilitates improving the dust and water resistance level of the device, while meeting the use of miniaturized wearable devices.

[0046] Figure 2A specific implementation of the antenna structure of the present disclosure is shown in FIG. Figure 2 The antenna structure of the present invention is described in detail.

[0047] For the sake of convenience, the direction in which the frame 120 surrounds the edge of the bottom shell 110 is defined as the "first direction". It can be understood that the "first direction" refers to the direction of the frame 120 surface surrounding the edge. For example, when the frame 120 is a circle, the "first direction" refers to the direction of the circle surrounding the edge, and the "length in the first direction" is the length of the arc; when the frame 120 is a circle, the "first direction" refers to the direction of the circle surrounding the edge, and the "length in the first direction" is the length of the arc. Figure 1b In the case of the rounded rectangular structure shown, the "first direction" refers to the direction of the rounded rectangle, and the "length in the first direction" refers to the length of the side of the surrounding rectangle. Figure 2 In the illustrated embodiment, the left-right direction shown in the figure is the first direction of the frame 120 , which should be understood by those skilled in the art and will not be described in detail.

[0048] like Figure 2 As shown, in this embodiment, the antenna structure includes a slot 210 opened on the frame 120, and the slot 210 has a first end 121 and a second end 122 opposite to each other in the first direction. The slot 210 refers to a through hole that passes through the side wall of the frame 120. The first end of the slot 210 is provided with an opening 220, and the opening 220 refers to a notch that opens one end of the slot 210. The opening 220 also needs to pass through the side wall of the frame 120, and the opening direction of the opening 220 is toward the side away from the bottom shell 110, that is, the upward direction shown in the figure, so that the structure formed by the opening 220 and the slot 210 is as shown in FIG. Figure 2 shown.

[0049] The feeding module is arranged on the main board inside the housing 100, and the feeding module is used to form electromagnetic waves of different resonant frequencies, so as to radiate outwards using the antenna structure formed by the feeding terminal 300 and the slot 210. The basic principle of the antenna should be understood by those skilled in the art, and the present disclosure will not repeat it. The feeding terminal 300 spans the width direction of the slot 210, is arranged between the first end 121 and the second end 122, and is close to the second end 122.

[0050] Based on the principle of slot antenna, feeding in the middle of the grounding points at both ends of the slot is equivalent to forming a dipole antenna with a wavelength of 1 / 2, and the length of the slot is 1 / 2 of the working wavelength. In this embodiment, an opening 220 is set at the first end of the slot 210, and the slot 210 with the opening 220 and the feeding terminal 300 together form a monopole antenna with a wavelength of 1 / 4, and the length L of the slot 210 is 1 / 4 of the working wavelength. For antennas with the same function, the antenna structure of this embodiment can reduce the opening length L of the slot 210 by half, which is suitable for relatively small wearable devices, such as smart bracelets, smart headphones, etc.

[0051] Specifically, the length L of the slot 210 in the first direction should be equal to 1 / 4 wavelength of a resonant frequency of the radiated radio wave. The functions implemented by the antenna structure are different, and the radiation bands are also different. For example, the central operating frequency of the Bluetooth antenna is 2.44GHz, while the central operating frequency of the civilian GPS satellite positioning antenna is generally 1.575GHz. Therefore, the length L of the slot 210 can be calculated based on different resonant frequencies. The relationship between the length L of the slot 210 and the operating frequency f of the electromagnetic wave is expressed as:

[0052]

[0053] In formula (1), L represents the length of the slot 210 in the first direction, λ represents the wavelength of the electromagnetic wave, C represents the speed of light, and f represents the resonant frequency of the electromagnetic wave. It can be seen from formula (1) that the length L of the slot 210 is inversely proportional to the operating frequency f of the antenna, that is, the lower the operating frequency of the antenna, the longer the required slot length is.

[0054] As can be seen from the above, when the device includes two or more antenna structures with different operating frequencies, the lengths of the slots 210 on the frame 120 are also different. This results in the device being unable to achieve a symmetrical structure in appearance, and as electronic devices have developed to date, appearance has long become an important consideration for people to choose electronic devices. Therefore, the present disclosure further provides some implementation methods that can further ensure the consistency of the device appearance while reducing the slots.

[0055] For ease of explanation, in this embodiment, a Bluetooth antenna and a satellite positioning antenna are used as examples for explanation. As can be seen from the foregoing, the central operating frequency of the Bluetooth antenna is 2.44 GHz, and the central operating frequency of a civilian GPS satellite positioning antenna is generally 1.575 GHz. The relationship between the gap length L1 of the Bluetooth antenna and the gap length L2 of the satellite positioning antenna can be calculated using formula (1), which is expressed as:

[0056]

[0057] It can be seen from formula (2) that the gap length of the Bluetooth antenna is approximately 0.65 times the gap length of the GPS satellite positioning antenna. If the two are opened on both sides of the shell, the difference between the opening gaps of the two is very large. The asymmetric gap makes the appearance of the device messy, which greatly reduces the user's perception and the grade of the device.

[0058] In this embodiment, the structure of the satellite positioning antenna is as follows: Figure 2 As shown, the length from the first end 121 to the second end 122 of the slot 210 is L2. When designing a Bluetooth antenna, refer to Figure 3As shown in FIG. 1A , the length from the first end 121 to the second end 122 of the slot 210 is still L2, which is consistent with the satellite positioning antenna. The Bluetooth antenna also includes a ground terminal 400, which is disposed in the slot 210 between the first end 121 and the second end 122. The ground terminal 400 spans the width of the slot 210, thereby dividing the slot 210 into two sub-slots on the left and right sides.

[0059] The feeding terminal 300 is disposed between the first end 121 and the ground terminal 400, and is close to the ground terminal 400. The function of the ground terminal 400 is equivalent to moving the ground end of the slot antenna to the position of the ground terminal 400, so that by changing the position of the ground terminal 400 in the first direction of the slot 210, the antenna can be adjusted to be suitable for different operating frequencies.

[0060] like Figure 3 As shown in A, in this embodiment, the distance from the first end 121 to the ground terminal 400 can be set to L1=0.65L2, so that the length from the first end 121 to the ground terminal 400 is equivalent to 1 / 4 wavelength of the Bluetooth antenna, realizing Bluetooth antenna radiation. Figure 3 The implementation method in A can be equivalent to Figure 3 Antenna structure in B.

[0061] In this embodiment, antenna structures with different working wavelengths can be realized by adjusting the position of the ground terminal 400 in the slot 210, thereby realizing antenna structures with different functions without changing the opening length of the slot 210. For example, when the device includes a Bluetooth antenna and a satellite positioning antenna, the two antennas can be respectively opened on opposite sides of the device, and the shape of the slot can be opened completely symmetrically, and the working length of the Bluetooth antenna can be adjusted by using the ground terminal 400, so that the device has better consistency and symmetry in appearance.

[0062] Of course, those skilled in the art can understand that the antenna structure of the present disclosure is not limited to the above two examples, and the device antenna is not limited to only the above two, and can also have any other suitable implementation forms, which will not be enumerated. In addition, when the consistency and symmetry of the device appearance are not required to be high, different antenna functions can also be achieved by directly opening gaps of different lengths, and the present disclosure does not limit this either.

[0063] Further, see Figure 2 , Figure 3It can be known from the antenna structure in that one of the inventive concepts of the antenna structure of the present disclosure is to open an opening 220 at one end of the slot 210, thereby forming a 1 / 4 wavelength slot antenna similar to a monopole, and shortening the opening length of the slot 210. As can be seen from the figure, the opening 220 structure will also make the antenna structure asymmetric in the first direction, affecting the consistency of the device appearance. Therefore, the present disclosure further provides some implementation methods, based on the above-mentioned inventive concepts, to further improve the consistency and symmetry of the device appearance.

[0064] like Figure 4 As shown, in some embodiments, a groove 230 is formed on the outer side wall of the second end 122 of the slit 210. Figure 4 As shown in A, the groove 230 and the opening 220 are symmetrical in shape in the first direction, but as shown in FIG. Figure 4 As shown in FIG. 2B , the groove 230 is only opened on the surface of the frame 120 and does not penetrate the thickness direction of the frame 120. In this way, after the gap is injection molded, it can be seen from the appearance that the gap 210 is a completely symmetrical structure in the first direction, and the groove 230 is a non-penetrating groove, which does not change the length and opening distribution of the gap 210, and thus does not have any performance impact on the original antenna structure.

[0065] After the antenna structure is formed, the gap needs to be filled with injection molding, for example, by using nano injection molding to fill the gap with non-metallic nanomaterials. On the one hand, the gap is sealed to improve the dust and water resistance of the device. On the other hand, the wavelength of the radiation signal will become shorter when it propagates in the dielectric material, so the use of filling medium can further reduce the opening length of the gap.

[0066] by Figure 4 For example, the appearance of the nanomaterial after filling is as follows. Figure 5 As shown, it can be seen that in the first direction, the shape of the slit opening is completely symmetrical, and the appearance consistency of the shell is better. Of course, those skilled in the art can understand that when the consistency and symmetry of the appearance of the device are not required, it is not necessary to set the groove 230, and the present disclosure does not limit this.

[0067] It is also worth noting that the wavelength of the cell wave in the medium will decrease as the dielectric constant increases, so the length of the gap can be reduced by using a filling material with a high dielectric constant. However, a medium with a dielectric constant that is too large will reduce the bandwidth and radiation efficiency of the antenna. Therefore, in this embodiment, a material with a dielectric constant of about 3.0 is preferred. Taking a satellite positioning antenna with a frequency of 1.575GHz as an example, in this embodiment, the gap length can be controlled at about 33mm, greatly shortening the length of the opening of the gap.

[0068] It can be seen from the above embodiments that the antenna structure of the present disclosure can be applied to wearable devices with metal shells. By setting an opening at one end of the slot, the feed and the slot form a 1 / 4 wavelength slot antenna, which greatly shortens the length of the slot opening. In addition, through the ground terminal, antenna structures with different functions can be realized without changing the length of the slot opening. The antenna structure is symmetrical in the first direction through the groove, and the appearance consistency of the device is better.

[0069] Further, Figure 8 The antenna structure in some other embodiments of the present disclosure is shown in FIG. In this embodiment, by setting a capacitor in the slot, the effective electrical length of the slot antenna is increased, and the length of the slot is further reduced at the same resonant frequency. Figure 8 Provide specific instructions.

[0070] like Figure 8 As shown, in this embodiment, the antenna structure further includes a first capacitor 500 , and the first capacitor 500 is connected across the gap 210 , that is, the two poles of the first capacitor 500 are electrically connected to the two sides of the gap 210 in the width direction.

[0071] It should be noted that the "feeding terminal 300 or the first capacitor 500 is disposed in the gap 210" mentioned in the embodiments of the present disclosure, and those skilled in the art should be able to understand how to implement the feeding terminal 300 or the first capacitor 500 based on the relevant technology. For example: the first capacitor 500 and the feeding terminal 300 are connected across the width direction of the gap. Figure 8 As shown, the positive (+) level of the feed terminal 300 and the first capacitor 500 is connected to the upper part of the slot, and the negative (-) level of the feed terminal 300 and the first capacitor 500 is connected to the lower part of the slot. In actual operation, the lower part of the slot and the PCB board of the system are electrically connected to each other through screws and metal shells on the PCB board. The feed terminal 500 of the slot can be implemented by a 50 ohm transmission line or a spring. When a 50 ohm transmission line is used to feed the slot antenna, the core (i.e., the positive pole) of the transmission line is connected to the upper part of the slot, and the outer conductor (i.e., the negative pole) of the transmission line can be directly connected to the ground of the PCB board. When a spring is used to feed the slot antenna, the core top of the spring (connected) is connected to the upper part of the slot, and the ground of the spring can be directly welded to the ground of the PCB board. Similarly, the first capacitor 500 can also lead out the upper part of the gap (i.e., the positive electrode of the capacitor) through the spring and connect it to an independent pad of the PCB, weld the positive electrode of the capacitor to the above-mentioned independent pad, and connect the other end (or negative electrode) of the capacitor to the ground of the PCB. Other methods of applying capacitance and feeding on both sides of the gap, as long as they play the role of applying capacitance and feeding on both sides of the gap, are within the scope of protection of this patent and will not be repeated here.

[0072] The generation of slot antenna resonance is essentially similar to that of a resonant circuit. Connecting a capacitor across the slot antenna is equivalent to increasing the capacitance of the resonant circuit, thereby correspondingly reducing the resonant frequency of the slot antenna. The reduction in the resonant frequency is equivalent to increasing the effective electrical length of the slot antenna, that is, at the same resonant frequency, the slot length of the antenna structure disclosed in the present invention can be smaller.

[0073] At the same time, according to the working principle of the capacitor, when the voltage difference applied to the two electrodes of the capacitor is larger, the effect of the capacitor is stronger. Therefore, the position of the first capacitor 500 should satisfy: the stronger the voltage value at the position of the first capacitor 500, the greater the degree of the antenna shift to the low frequency, that is, the higher the effective electrical length of the antenna.

[0074] Therefore, for the 1 / 4 wavelength slot antenna in this embodiment, analyzing its resonant voltage distribution shows that in the direction from the first end 121 to the second end 122, the voltage gradually decreases, that is, the voltage value at the opening 220 is the largest, and the voltage value at the ground end is zero. Therefore, in this embodiment, in the first direction, the first capacitor 500 is set at an end close to the opening 220, that is, the end close to the first end 121 in the figure. Thereby, the stronger the capacitance effect, the greater the effective electrical length of the antenna, that is, at the same resonant frequency, the opening length of the slot can be reduced.

[0075] On this basis, different capacitance values ​​will also have an impact on the performance of the antenna. According to the principle of capacitance, it satisfies: the larger the capacitance value of the applied first capacitor, the stronger the effect of shifting the antenna resonant frequency to low frequency, that is, the longer the effective electrical length of the antenna. However, it should be noted that the size of the applied capacitance value is inversely proportional to the efficiency of the antenna, so the smallest capacitance value should be used as much as possible to ensure the performance of the antenna. However, the antenna resonant frequency can be fine-tuned by changing the capacitance value, which can be understood by those skilled in the art and will not be elaborated.

[0076] It should be noted that the concept of this embodiment is to increase the effective electrical length of the antenna slot and reduce the operating frequency of the antenna by adding capacitance to the slot antenna at the same slot length; that is, under the condition of achieving the same operating frequency, the antenna structure disclosed in this invention can reduce the slot length. Figure 8 The structure shown can achieve corresponding effects by applying capacitance on the basis of any of the aforementioned implementations, which will not be enumerated in the present disclosure.

[0077] In a second aspect, the embodiments of the present disclosure provide a wearable device, which includes the antenna structure in any of the above embodiments. The wearable device described in the present disclosure can be any type of device suitable for implementation, such as wrist-worn devices such as smart watches and smart bracelets; head-worn devices such as smart headphones and smart glasses; wearable devices such as smart clothing; etc., and the present disclosure does not limit this.

[0078] In an exemplary embodiment, the wearable device is a smart watch, which is a watch with a metal shell. The structure of the shell is shown in FIG. Figure 1a and 1b As shown in the implementation method, no further details are given. A mainboard (not shown in the drawings) is arranged inside the housing, and the mainboard includes a feeding circuit, and the feeding terminal of the antenna structure is connected to the feeding circuit of the mainboard. The smart watch includes a Bluetooth antenna and a satellite positioning antenna, and the satellite positioning antenna is, for example, a GPS satellite positioning antenna, a Beidou satellite positioning antenna, etc. Those skilled in the art should understand this and will not be described in detail.

[0079] like Figure 1a As shown, the Bluetooth antenna 201 and the satellite positioning antenna 202 are symmetrically arranged on the frame 120 on the opposite sides of the shell. In this embodiment, the Bluetooth antenna 201 and the satellite positioning antenna 202 adopt a completely symmetrical structure in the above embodiment, that is, the Bluetooth antenna 201 uses the ground terminal 400 to achieve the same length of the first gap of the Bluetooth antenna 201 and the second gap of the satellite positioning antenna 202. It can be seen that from the appearance of the shell, whether it is the two antennas on the opposite sides or each antenna, they are symmetrical structures, and the appearance of the device is more integrated. And in this embodiment, the shell does not need to have an annular gap, which greatly reduces the gap length of the frame, making the structure of the watch stronger and higher, and the waterproof level is higher.

[0080] It is understandable that the above examples are only used to illustrate the present disclosure and do not limit the present disclosure. In other embodiments, the number of antennas of the watch can also be any other number suitable for implementation, such as only providing a satellite positioning antenna on the device housing and setting the Bluetooth antenna inside. For another example, in addition to satellite positioning and Bluetooth antennas, the device can also include WIFI antennas, LTE antennas, 5G antennas, etc. if the volume permits. Wearable devices can also be other types of devices, such as headphones, bracelets, etc. And the shape of the shell is not limited to the above-mentioned rectangular structure, but can also be any other shape suitable for implementation, such as a circle, etc., which will not be repeated in this disclosure.

[0081] exist Figure 1b In the example shown, the gap width W of the two antennas is taken as a typical size of 1.2 mm, and the length ratio of the feeding terminal 300 to the ground terminal is taken as 0.1 to 0.2. Figure 6FIG. 1 shows the return loss curve of the satellite positioning antenna and the Bluetooth antenna of the watch and the isolation curve between the antennas in this embodiment. Figure 6 The results show that, in this embodiment, the satellite positioning antenna and the Bluetooth antenna not only have good return loss but also have high isolation between the two antennas.

[0082] Figure 7 2 shows the radiation efficiency and total efficiency curves of the satellite positioning antenna and the Bluetooth antenna of the watch in this embodiment. It can be seen that the antenna structure in this embodiment has high radiation efficiency and total efficiency and good antenna performance.

[0083] From the above, it can be seen that the embodiments of the present disclosure provide a wearable device with an all-metal shell, better structural strength and appearance texture, and a smaller antenna gap. The device has better integrity and appearance, has a good look and feel, and improves user experience.

[0084] Obviously, the above embodiments are merely examples for clear explanation, and are not limitations on the embodiments. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. For example, the opening position of the slot antenna may not be above the metal middle frame, but on the bottom shell or other positions, as long as an opening is provided at the end of the slot away from the feeding end to form a (1 / 4) wavelength slot. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. An antenna structure, characterized in that: Applied to a wearable device, the wearable device includes a metal shell, the shell includes a bottom shell and a frame surrounding an edge of the bottom shell and integrally connected to the bottom shell, the antenna structure includes: A slit is provided on the frame, wherein the slit has a first end and a second end located on opposite sides in a first direction, wherein the first direction is a direction surrounding the edge of the bottom shell; the slit is provided with an opening at the first end, wherein the opening faces a side away from the bottom shell; and in the first direction, a length from the first end of the slit to a ground end is 1 / 4 of an operating wavelength; A feeding terminal is provided between the first end of the gap and the ground end and is located close to the ground end, wherein the feeding terminal is connected to a feeding module on a mainboard of the wearable device.

2. The antenna structure according to claim 1, characterized in that: The second end of the slot forms the ground end.

3. The antenna structure according to claim 1, characterized in that: Also includes: A grounding terminal is provided in the slot and located between the first end and the second end. The grounding terminal divides the slot into an independent first sub-slot and a second sub-slot in the first direction. The grounding terminal forms the grounding end.

4. The antenna structure according to claim 1, characterized in that: A groove is formed on the outer side wall of the second end of the slit, and the groove is symmetrical with the opening in a first direction.

5. The antenna structure according to claim 1 or 4, characterized in that: The gap is filled with an injection-molded structure that matches the shape, and the injection-molded structure is made of non-metallic material.

6. The antenna structure according to claim 1, characterized in that: Also includes: A first capacitor is provided in the gap, and two electrodes of the first capacitor are respectively connected to two sides of the gap in a width direction; In the first direction, the first capacitor is located at one end close to the opening.

7. The antenna structure according to claim 1, characterized in that: In the first direction, the distance between the feeding terminal and the ground end is a first length, the distance between the first end and the ground end is a second length, and the ratio of the first length to the second length is 0.1 to 0.

2.

8. A wearable device, characterized in that: Comprising the antenna structure according to any one of claims 1 to 7.

9. The wearable device according to claim 8, characterized in that: It includes a Bluetooth antenna and a satellite positioning antenna, wherein the Bluetooth antenna and the satellite positioning antenna are the antenna structure and are respectively arranged on two opposite sides of the frame; The first slot of the Bluetooth antenna and the second slot of the satellite positioning antenna are symmetrical in shape, and the length from the first end of the first slot to the ground end is 1 / 4 of the working wavelength of the Bluetooth antenna, and the length from the first end of the second slot to the ground end is 1 / 4 of the working wavelength of the satellite positioning antenna.

10. The wearable device according to claim 8, characterized in that: The wearable device is a smart watch or a smart bracelet.

Images